LOS ANGELES (AP) — Scientists believe NASA's Phoenix Mars lander exposed bits of ice while digging in the soil of the Martian arctic in recent days.

Principal investigator Peter Smith said Thursday that crumbs of bright material seen in the trench have since vanished. He says that means it must have been frozen water that vaporized after being exposed.

Scientists had also considered whether the specks might be salt. Smith points out that salt wouldn't have vaporized.

The lander is on a mission to discover whether the polar environment could be favorable for primitive life to emerge.